ControlLogix Subroutines

dash

Lifetime Supporting Member
Join Date
Jun 2003
Location
Birmingham, AL
Posts
589
I have allways been frustrated that the CLX subroutines do not give you a way to develop a true function block routine (like in Wago & Siemens) where you can declare each use of the function block and it keeps each instance separate. I also miss true pointer based addressing which makes a lot of that possible.

Any how this is my closest approximation of how to uses some of the more common features of timers and counters with UDTs & create truly reusable subroutines. I have not seen a Rockwell example like this, but I may have not searched on quite the right terms.

Does anyone have a better solution, comments, etc?

udt_testing.jpg
 
Last edited:
What I typically do is pass in the UDT as well as any specific parameters I know will change as separate inputs. It's similar to a classical Siemens S7-300 muli-instance FB call where the instance data block goes on top and the input parameters get stuck in the side. In the CLX case the UDT gets passed in AND out. That way you don't need to do the single bit mapping like you show in your example. You just use the BOOLs as inputs. The real downfall for the AB implementation IMHO is the lack of descriptions in the input and output fields. You need to know what each input and output position mean. This is a real nice thing from the Siemens Step7 method that I would really like to see in the AB method.

Keith
 
Thanks for commenting. That example was probably to basic & without any comments. I was just trying to see if counter/timers would retain state by passing the UDT as an input & output. I am creating a more detailed example to hopefully create more comments/interest.

What I miss from the Wago is the ability to use pointers to address directly to the IO without all the intermediate logic.

Darren
 

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